Method for positioning components on a cylindrical member

ABSTRACT

The method and apparatus are useful in positioning components, for example two half shells of a clamp for a pipeline or other cylindrical member (10). One half-shell (12) is clamped by studs (56) to brackets (52) on a carriage (16) which can then traverse about the member (10) by engagement of sprockets (30, 28) with chains (18) encircling the member (10). A second half-shell is then lowered by crane onto the member (10). The two half shells are clamped together by studs and the brackets (52) released and swung clear. The apparatus can then be removed if desired. Drive to the carriage (16) is through a flexible shaft (70), gearbox (34) and sprockets (30) connected together by drive shaft (33). Wheels (26) roll on the member (10).

The invention relates to methods and apparatus for positioningcomponents.

According to the invention, a method of positioning particularcomponents against a cylindrical member using a carriage which canexecute traversing movements about the member, said carriage beingdriven during said traversing movements by sprockets engaging stationarychain means encircling said member, comprises effecting support of afirst component upon the carriage, moving the carriage and the firstcomponent about the member and placing a second component in theposition previously occupied by the first component.

According to the invention apparatus for positioning particularcomponents against a cylindrical member comprises a carriage which cantraverse around said member, chain means which encircle the member andare engaged by sprockets on the carriage and first releasable means onthe carriage by which a first component can be supported.

The method and apparatus for performing it will now be describe by wayof example with reference to the following drawings in which -

FIG. 1 is a perspective view of the apparatus showing a first componentsupported about a cylindrical member; and

FIG. 2 is an end view of the apparatus (partly in vertical section) 180degrees in relation to the position shown in FIG. 1 and showing a secondcomponent (in chain outline) supported by the cylindrical member.

FIG. 1 shows a cylindrical member 10 such as a pipeline or cylindricaltubular member of a drilling platform or rig. It is required to positiontwo semi-cylindrical components (or half shells) about the cylindricalmember 10 to clamp the cylindrical member 10. For example, thehalf-shells may be the half-shells or a repair clamp.

One of the components 12 is shown in FIG. 1 and the other 14 is shown inFIG. 2 in chain outline.

The apparatus for positioning the components 12, 14 comprises a carriage16 and two endless chains 18 which encircle the member 10. The carriage16 can traverse around the member 10 by engagement with the chains 18.

Each half of the carriage 16 comprises a beam 20 having adjacent eachend a tube 22, connected to a pair of triangular plates 24 carryingpairs of wheels 26 engaging the outer surface of the member 10. Eachpair of wheels 26 is fast with a sprocket 28 arranged between the wheels26 and engaging a chain 18.

Each chain 18 is engaged by further sprockets 30, 32. The two sprockets30 are inter-connected by a drive shaft 33 driven by a gearbox 34. Thesprockets 32 are idler sprockets and they are not interconnected. Thechains 18 are tensioned by a further sprocket (not shown) at 40 (FIG. 2)positioned by a bolt 42. The ends of the pairs of triangular plates 24remote from the beams 20 are interconnected by a strap 44 and ratchetfastener device 46 (FIG. 2).

The two halves of the carriage 16 are interconnected by two bars 50which enter holes in the plates 24. Pivoted on each bar 50 are twobrackets 52. Each bracket 52 has a cantilever end piece 54. The endpiece 54 has a through-hole with its axis parallel to the length of thebracket 54. A stud 56 extending through the hole affords support for thefirst component 12, together with nuts 58, 60, 62, 64 (FIG. 2). One ofthe studs 56 is omitted from FIG. 2. The studs 56 enter the end holes ofa series of three holes in each flange of the first component 12. Themiddle hole of the three is just visible in FIG. 1 at 66.

To position the carriage 16 and the chains 18 the following procedure isadopted The two half-carriages, each consisting of a beam 20 and wheeledassemblies at the ends of the tubes 22 are lifted and set onto the pipeor other cylindrical member 10 about the area desired to be repaired orclamped for other reasons. The beams 20 are located relative to oneanother by temporary spacers (not shown). Both half-carriages remainattached to the crane point at this stage. In each half-carriage, theleft-hand tube 22 (as seen in FIG. 2) is hinged to its respective beam20 to facilitate fitting of the wheel assemblies around the member 10.The hinge incorporates a locking mechanism. Some yielding may be allowedto cater for lack of circularity in the member 10.

The circumferential chains 18 are fed through the wheel and sprocketcarriages 16 secured by a breakable link and tensioned by the screws 42.The straps 44 are passed around the member 10 and tightened.

The drive shaft 33 is connected. The bars 50 with the brackets 52 areconnected. The two carriage halves are disconnected from the crane slingand the temporary spacers are removed.

The component 12 is lowered by the crane onto the upper half of themember 10. The studs 56 and the nuts 58, 60 and 62 are used to connectthe components 12 to the brackets 52. The component 12 is lifted by thenuts on the studs to the position shown in FIG. 1 with sufficientclearance between the component and the member 10 to allow the nextstep.

The crane sling is removed from the component 12.

The gearbox 34 is operated to transmit drive from the flexible driveshaft 70 to the draft shaft 33 and the sprockets 30. The carriage 16 andthe component 12 is turned through 180 degrees about the member 10 tothe position shown in FIG. 2. The shaft 70 is manually operable or elsea motor (not shown) is used to drive the shaft 70.

The nuts 64 are removed and the second component 14 is lowered by craneonto the member 10. The studs 56 and the brackets 52 act a locationguides.

Studs (not shown) are positioned in the central hole 66 and tightenedusing nuts (not shown). The crane sling is removed. The other studs 56and the nuts 58, 60, 62 and 64 are released, the brackets 52 are swungclear and the studs 56 are fastened in the end holes, of the twocomponents using two nuts per stud.

The two components 12, 14 are now fully tightened against one another,compressing the seals (not shown), located on their inner sides, againstthe member 10.

The apparatus is then removed or, if it is too costly to do so (forexample, in the sub-sea operations) it is left in place as it does notinterfere with the effectiveness of the clamp components 12, 14.

Although the clamp described is made up of two halves, some other typesof clamp are made up of a different number, for example three componentseach extending some 120 degrees around the member 10. The inventionapplies also to a method and apparatus for positioning such clamps.

In modifications (not shown) carriages may be mechanically linked toaccommodate sub-assemblies enclosing single or multi-mode structures ofcylindrical members (e.g. in sub-sea structures). The number of sprocketand chain arrangements may be varied to handle increasing size andweight of component. An axial mechanical linkage may be provided on theend of the shaft 33 and a belt encircling the pulley and the member 10,may also provided to give encastre coupling with the carriage as atechnique to counteract end movements or tilting movement. Also the sametechnique can provide additional braking to prevent circumferentialslipping of the chain 18.

What is claimed is:
 1. A method of positioning first and secondpart-circular components against a cylindrical member using a carriagewhich can execute circular traversing movements about the cylindricalmember, said carriage being driven during said traversing movements bysprockets engaging a stationary chain encircling said cylindricalmember, said method comprising the steps of: effecting support of thefirst component upon the carriage, moving the carriage and the firstcomponent about the cylindrical member, and placing the second componenton the cylindrical member in the position previously occupied by thefirst component.
 2. A method according to claim 1 wherein said movingstep moves the carriage and the first component 180 degrees about thecylindrical member; wherein said placing step places the secondcomponent in a sector previously occupied by the first component; andfurther including the step of transferring support of said firstcomponent from the carriage to said second component.
 3. A methodaccording to claim 2, wherein the support between said carriage and saidfirst component, and subsequently the support between said secondcomponent and said first component are effected by tightening nuts ontostuds carried by the supporting carriage and by the second component.